why need to use array function in mql4

Question

I really not satisfied with mql4 array function.In mql4 reference they cannot explain why need to use this function. example why I need to use arrayinitialize function

Answer 1

When you declare some array, it may contain some garbage there. Most likely you will have default values, like 0 or NULL but garbage may stay there as well. By use of 'ArrayInitialize()` function you can be sure that all the values in your array are the values you've put there.

string arr2str(const int &array[])//fn to print array, ugly, ends with ,|
  {
   string result="|";
   for(int i=0;i<ArraySize(array);i++)
     {
      result+=(string)i+"="+(string)array[i]+", ";
     }
   return result+"|";
  }
void OnTick()
  {

   int array[8];
   printf("1: %d. %s",ArraySize(array),arr2str(array));
   //receive: 1: 8. |0=0, 1=0, 2=0, 3=0, 4=1995110657, 5=146315416, 6=1, 7=85975080, |
   int result=ArrayInitialize(array,7);
   printf("2: %d %d. %s",result,ArraySize(array),arr2str(array));
   //receive: 2: 8 8. |0=7, 1=7, 2=7, 3=7, 4=7, 5=7, 6=7, 7=7, |

   ExpertRemove();//to stop the test
  }

As you can see, first array output (1:) has some strange data. After initialization, no problem with it (2:) - all are sevens since I put 7 as second param in the function, it could be and most likely 0 instead of 7 in your codes.